title: Bendiocarb resistance in Anopheles gambiae s.l. populations from Atacora department in Benin, West Africa: a threat for malaria vector control.
abstract: BACKGROUND
  Owing to pyrethroid resistance in An. gambiae, the carbamate and organophosphate insecticides are currently regarded as alternatives or supplements to pyrethroids for use on mosquito net treatments. Resistance monitoring is therefore essential to investigate the susceptibility of An. gambiae s.l to these alternative products.
  
  
  METHODS
  Two to three day old adult female Anopheles mosquitoes were reared from larvae collected in the five districts (Kouandé, Natitingou, Matéri, Péhunco, Tanguiéta) of the Atacora department. Mosquitoes were then exposed to WHO impregnated papers. The four treatments consisted of: carbamates (0.1% bendiocarb, 0.1% propoxur) and organophosphates (0.25% pirimiphosmethyl, 1% fenitrothion). PCR assays were run to determine the members of the An. gambiae complex, the molecular forms (M) and (S), as well as phenotypes for insensitive acetylcholinesterase (AChE1) due to ace-1(R) mutation.
  
  
  RESULTS
  Bioassays showed bendiocarb resistance in all populations of An. gambiae s.s. tested. Propoxur resistance was observed in Matéri, Péhunco and Tanguiéta, while it was suspected in Kouandé and Natitingou. As for the organophosphates, susceptibility to pirimiphos-methyl was assessed in all populations. Fenitrothion resistance was detected in Kouandé, Péhunco and Tanguiéta, while it was suspected in Matéri and Natitingou. The S-form was predominant in tested samples (94.44%). M and S molecular forms were sympatric but no M/S hybrids were detected. The ace-1(R) mutation was found in both S and M molecular forms with frequency from 3.6 to 12%. Although the homozygous resistant genotype was the most prevalent genotype among survivors, the genotypes could not entirely explain the bioassay results.
  
  
  CONCLUSIONS
  Evidence of bendiocarb resistance in An. gambiae populations is a clear indication that calls for the implementation of insecticide resistance management strategies. The ace-1(R) mutation could not entirely explain the resistance to bendiocarb observed and is highly suggestive of involvement of other resistance mechanisms such as metabolic detoxification.
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. rockypremier@yahoo.fr
authors.forename: Rock
authors.initials: R
authors.lastname: Aïkpon
authors.forename: Fiacre
authors.initials: F
authors.lastname: Agossa
authors.forename: Razaki
authors.initials: R
authors.lastname: Ossè
authors.forename: Olivier
authors.initials: O
authors.lastname: Oussou
authors.forename: Nazaire
authors.initials: N
authors.lastname: Aïzoun
authors.forename: Frédéric
authors.initials: F
authors.lastname: Oké-Agbo
authors.forename: Martin
authors.initials: M
authors.lastname: Akogbéto
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics; D000818:Animals; D000852:Anopheles / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D001541:Benin; D001681:Biological Assay; D005260:Female; D005838:Genotype; D006801:Humans; D007303:Insect Vectors / Q000187:drug effects*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D008288:Malaria / Q000517:prevention & control / Q000635:transmission; D009032:Mosquito Control / Q000379:methods; D009154:Mutation; D048448:Phenylcarbamates / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D016019:Survival Analysis
chemical_list: D007306:Insecticides; D048448:Phenylcarbamates; D000110:Acetylcholinesterase; C007725:bendiocarb